Ultra high frequency communication system



Nov. 12, 1935. v R. GUNN 2,020,310

ULTRA HIGH FREQUENCY COMMUNICATION SYSTEM Filed July 26, 1952 r 2Sheets-Sheet 1 INVENTOR Ross Gu 7272 ATTORNEY Nov. 12, 1935.

R. GUNN 'ULTRA HIGH FREQUENCY COMMUNICATION SYSTEM Filed July 26, 1932 2Sheets-Sheet 2 nvun'u F 5/ v k L N INVENTOR Ross Gunn ATTORNEY PatentedNov. 12, 1935 UNITED STATES ULTRA HIGH FREQUENCY COMMUNI- CATION SYSTEMRoss Gunn, Chevy Chase, Md. Application July 26, 1932, Serial No.624,877

6 Claims. (01. 250 36) (Granted. under the act of March 3, 1883, asamended April 30, 1928; 370 0. G. 757) This invention relates to highfrequency communication systems, and more particularly to ultra highfrequency communication systems and has for one of its objects toprovide improved means for generating oscillations of high frequencieswithin the quasi-optical range. 7

Another object of this invention is to provide means for producingconsiderable amounts of power in theform of ultrahigh frequencyoscillations.

Another object of this invention is to provide a system employingelectronic oscillations wherein the electrons or ions oscillating withina tube are controlled as to phase whereby neutralizing effects of amultitude of electrons or ions oscillating in different phasesareavoided.

Another object of this invention is to provide 7 a receiver that issensitive and highly selective to radiation of 'ultra high frequencies.

'Another object ofthis invention is to provide a means forconcentrating, directing and scatter ing ultra high frequency radiation.

Another object of this invention is to provide electron dischargeapparatus of novel construction that is particularly adapted for use inconnection with the production and reception of ultra high frequencyoscillations. I

With the above and other objects in view, the invention consists in theconstruction, combination and arrangement of parts as will be describedmore fully hereinafter. V

Oscillation generators of the conventional type employing negativeresistance in combination with resonant circuits usually do not workwell or at all in the ultra high frequency or quasi-' optical range.Generators of the so-called Barkhausen-Kurz or Gill-Morrell typeemploying electronic oscillations are found to work at quasiopticalfrequencies, but the output and efliciency of this type of generator hasbeen extremely small. V

The present invention is concerned with improvements of systemsemploying electronic oscillations wherein their properties are greatlyenhanced byproper adjustment of the phase of the moving particles.

receiver. type tube;

Fig. 3 is a diagrammatic showing of a transmitter employing a tubesimilar to the tube shown in Fig. 1; p

Fig. 4 is a diagrammatic showing of a receiver employing a tube similarto the. tube shown in 5 Fig. 2; Fig. 5 shows diagrammatically a beamtransmitter with means to concentrate reflect, difiract and scatterultra high frequency radiation.

Referring now to Fig. l, a filamentary cathode is shown at I00 mountedwithin an evacuated envelope 3 and provided with leads I and 2 forsupplying heating current thereto. Displaced from the filament I09within the envelope 3 are a plurality of tuned resonant systems 5-6,'l8, IUI I, l2l3. Tuned conductors 56 and '|-B lying within the sameplane are supported nodally at their midpointsby a conductor 4 whichconstitutes a lead for supplying the necessary direct current potentialto these elements. Tuned conductors IUII and l2l3 are supported nodallyat their midpoints by a conductor 9 which constitutes a lead for'supplying the necessary direct current potential to these elements.Leads I4 and 25 coupled to the resonant element 18 are for 25" thepurpose of transferring the high frequency oscillations existing on thiselement to a tuned radiator of appropriate type. In Fig. 1, leads I 4and I5 are shownassociated with tuned element 18, although it is to beunderstood that these 30 W The structure of the tube shown in Fig. 2 isidentical with that of Fig. 1 except that tuned element IBI9 supportedat its midpoint by a conductor 20, which serves as a lead thereto, has

been added. The tuned element l8--|9 occupies a position within thespace generally surrounded by tuned elements 56, .18, lfll I, l2l3, and

is parallel thereto.

Because of the high voltages desirable for ultra frequencies, the tubestructure must be quite rigid. It is desirable that the oscillatingconduc- 45 tor tuned elements be supported at the node. Evidently thetuned elements 56, etc., can be approximately any number of halfwave-lengths long or they can contain concentrated inductance orcapacity values for securing special adjust- 50 ments of phase withoutdeparting from the basic ideas. It is evident, moreover, that arrays oftubes properly arranged in space will give rise to directive beams, etc.

Fig. 3 is a diagrammatic showing of the tube of Fig. 1 connected incircuit with appropriate sources of potential for the generation andradiation of high frequency oscillations. Coupled to the tuned resonantelement 'I8 is a radiating system 5| located at an appropriate distancein front of a parabolic metallic mirror 50: Tuning devices 54 and 55 areconnected in the coupling leads I6 and I1 between the radiating system5! and the tuned resonant system 7-8 within the tube for adjusting thecircuit for efficient transfer of energy to the radiating system. Thebattery 56 is connected to leads I and 2 so as to energize the filamentI00. The battery 51 is connected between the filament and the tunedresonant system 5-6, etc., and is so poledthat the-tuned system isnormally positive with respect to the filament. The battery 58 isconnected between the filament and the radiating system II J -II,

etc., and is so poled that the tuned system Ill-4 I etc. is normallyhighly positive with respect to the filament. In the drawings,thepotential applied between the filament-I00 and the tuned system I0IIis shown as being derived from batteries 51 and 58 in series although itis to be understood that a separate battery or other source of potentialof proper value may be used instead of the two batteries connected inseries.

A magnetic field is applied to the tube for use at the highestfrequencies. This magnetic field may in general be applied by means oftwo-units, one designed to produce a very intense field, say- 5000gauss, in a direction parallel to the electric field, the other ofmoderate value between 0 and 2000 gauss, depending on the frequencydesired and the spacing of the elements, is applied in a direction atright angles to both the electric field and the oscillating dipole.

The units for applying magnetic fields to the tube 3 are shown inFig. 1. (A showing of these units has been omitted from Fig. 3 for thesake of clarity.) Magnetizing coils 60 and BI are disposed on oppositesides of the tube 3 with their axes passing through the tube normal tothe oscillating dipoles and the principal electric field within thetube. These coils are shown connected in series and provided with leads62 and 63 which may be connected to an appropriate source of potentialby way of a variable resistor. Magnetizing coils 64 and 65 are disposedon op- ;posite sides of the tube 3 with their axesparallel to theprincipal electric field within the tube. Coils 64 and 65 are shownconnected in series, although it is to be understood that they'may beconnected in parallel as may the coils 60 and 6|;

Coils 64 and 65'are provided with leads 66 and magnetic substances maybe used for cores of these magnetizing coils.

The oscillations of ultra frequency, or ultra high frequency that we mayexpect in this system are:

(a) Electronic oscillations.

(b) Oscillations in tuned resonators as a result of electronic shockexcitation.

(0) Phase oscillations.

In general, the electronic oscillations of Bark- 1hausen-Kurz are veryfeeble because there are a great many electrons in the tube and theyhave no definite phase relation to each other so tha the mutualradiation largely cancels out. 4 Consider in Fig. 1 a single electronfrom th hot filament connected to electrodes I and 2, and

suppose that it heads for the rod 'I8, passing midwaybetween theelectrodes I 0I I and I2-I3. When the electron passes through the planedetermined by I0I II2I3 it has its maximum energy and velocity whichwill be lost by the time it reaches the electrode 'I--8. The directionof the force reverses as it passes through the plane of electrodesI0'III2-I3 and therefore by proper positioning of the electrodes, theelectric field on each side of the plane can be made roughlyproportional to the distance from the plane. That is to say, theelectric field is purposely made inhomogeneous.

Suppose the space charge is small and let this proportionality beexpressed by v E=ky (1) where E is the electric field, y the distance of{the selected point from the plane and k the pro- 2 v=ef d Now the forceF on the electron is F=Ee= ke1y where e is the electronic charge and 61is its abso- U lute magnitude. Thus the electron executes simpleharmonic motion of frequency This relation shows clearly that forextremely high frequencies the applied potential V must be moderatelyhigh and the spacing s kept as small as is consistent with structuraldifficulties. The operation of the system shown in Fig. 3, while notdefinitely understood, is believed to be as follows. The filamentarycathode I00 is heated by current from source of potential 56 and emitselectrons. cathode I00 are transferred to the region be-. tween thetuned elements by the source of potential 51 operating via lead 4 andthe element 5--6 which acts as a space charge electrode. The source ofpotential 51 is of such value that high current densities are notrequired. The electrons passing into the region between the tunedelements of the system are accelerated toward the plane formed by theanode elements Ill-II and I2I3 as a result of the electric fieldproduced by the battery or other source of potential 58. Due tonon-symmetry in the way the electrons initially come off, the. tunedresonant systems 5- -6, I0--II and I 2I3 individually and as a systemare shock excited and resonate at their own natural frequency. The,electric field, due to the oscillating potential of the resonators,causes'the electric field between the filament I00 and parts of theresonator 5-6 to change with time; thus, when the end 5 is at a'higherpositive potential with respect to the filament than its mean (steady)value, more electrons will come across at that end than at the end 6.One-half a cycle later more electrons will come across at the end 6,while the end 5 will be so charged as to block the flow of electronsadjacent thereto and the' phase of the electronic oscillations'willbecontrolledby the varying potential on the ,dipole resonators andradiation from the electron The, electrons, emitted from.

with an auxiliary electrode similar to the tube shown in Fig. 2. Thefilament I00 is energized from battery 3| by means of the leads I and 2.Positive potential is applied to the tuned resonant system comprisingelements 56, etc., from battery 32 connected to the filament I00 andlead 4. Positive potential is applied to the tuned resonant systemcomprising elements ill-4 l, etc., from battery 33 via lead 9. Thus farthe receiver is identical with the transmitter except that the batteries3| and 32 are of lower potential than are used in the transmitter inorder that the electron emission be kept at a proper value for receivingpurposes. The tuned resonant electrode l8|9 is connected at its midpointby means of lead 20 to one end of the primary winding 34 of transformer36. The other end of the winding 34 is adapted to be connected to thebattery 32 at a point more positive than the filament. Coupled to theprimary 34 is a secondary 35 which is connected to the filament 38 andgrid 39 of a suitable thermionic amplifying device. A battery 31 isconnected to the filament 38 for heating the same. A battery 43 isconnected to the filament 3B and through the receiver 4| or other typeof indicator to the anode or plate 40 of the tube. A condenser 42 isconnected between the anode 40 and the filament. Coupled to the tunedsystem 1-- 8, etc., is a receiving antenna 26 located at the properdistance in front of a parabolic metallic mirror 25. Leads 21 and 28between the antenna 26 and the tuned system 18 are provided with tuningcondensers 29 and 30 for tuning the system to effect the most efficienttransfer of energy therebetween.

The operation of the receiver, while not definitely understood, isbelieved to be as follows:

The radiated waves from the transmitter traverse the distance from thetransmitter to the receiver where theyare converged or focused upon thereceiving antenna 26 by the mirror 25. Antenna 2% then has inducedtherein high frequency oscillations of the frequency of the transmittedwaves to which it is tuned. These high frequency oscillations arecoupled by way of the condensers 29 and 30 to tuned resonant system 'l8,etc., which is caused to oscillate at the frequency of these waves. Thetotal space current through the tuned system l8-l9 is controlled bythese oscillations in some manner not well understood. This currentcontrolled in accordance with the received oscillations passes throughlead 20 to the transformer primary 34 and thence back to the battery 32and filament I ill], inducing currents in the secondary to control theoutput of the amplifier tube in well known manner. Obviously, any typeof amplifier could be used instead of the one shown, or the output ofthe receiving tube could be coupled directly to a receiver or other typeof indicator instead of to the transformer winding 34. 1

The ultra frequencies have substantially optica properties and normallycan be propagated only in straight lines. In general, a beam transmitteris used and the energy in the beam is very large and confined to a smallarea. Suppose it should be desired to transmit to stations A, B and C(Fig. 5), as well as station N. This may still be accomplished byplacing a scatterer or director at the point L, say, which absorbs andemits or refracts some of the incident energy toward the desiredstations A, B or 0. Many devices will serve to scatter or refract thewaves, as for instance:

(a) Tuned resonant circuits or arrays of them. 7 (1)) Lens systems.

(c) Diffraction gratings of various kinds. (d) Metallic reflectors. Thismethod of diffraction permits the transmission of the ultra frequencybeyond the bulge of the earth around skyscrapers, bridges, etc. I

It is to be understood that any appropriate system of modulation may beused in connection with the above disclosed transmitter. The amplitude,frequency or phase or any combination of the three may be controlled byelectrical means,

or the beam transmitted may be controlled di rectly by shutters in muchthe same way as is done with visible light in heliograph signalingsystems.

The invention herein described may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalty thereon.

I claim:

1. In an oscillation generating system for generating oscillations ofultra-high frequency, an electron discharge device having a linearcathode, a tuned anode system comprising a pair of linear elementsparallel to said cathode defining a plane displaced from said cathodeand a tuned space charge electrode system comprising a pair of linearelements parallel to said cathode defining a plane that intersects theplane of said anode, each of said linear elements of said anode andspace charge electrode being tuned to the ultrahigh frequency to bederived from said system, means for causing said cathode to emitelectrons, means for causing some of the emitted electrons to be drawntoward the plane of said anode to execute Barkhausen-Kurz electronicoscillations, and means comprising said tuned space charge electrode andsaid anode for controlling the oscillation of electrons in accordancewith the changing potential distribution existing on said tuned spacecharge electrode.

2. In an oscillation generating system for generating oscillations ofultra-high frequency, an electron discharge device having a linearcathode, a tuned anode system comprising a pair of linear elementsparallel to said cathode defining a plane displaced therefrom and atuned space charge system comprising a pair of linear elements parallelto said cathode defining a plane that inter sects the plane of saidanode, each of said linear elements of said anode and space chargeelectrode systems being tuned to the ultra-high frequency to be derivedfrom the system, means for heating said cathode, a source of highpotential, means connecting the low potential side of said source tosaid cathode, means connecting the high potential side of said source toa potential nodal point on said anode system, and means for biasing thetuned space charge system at a potential intermediate the potentialbetween said cathode and said anode system.

3. An ultra-frequency oscillation generating system, comprising anelectron discharge device having a linear cathode, an anode systemcomprising a plurality of mutually parallel electrically resonant linearelements tuned to the ultra-frequency to be generated, an additionaltuned electrode system comprising a plurality of mutually parallelelectrically resonant linear elements tuned to the same said frequencyand arranged parallel to each other and to said anode system andoccupying a different plane therefrom, a source of high potential, meansconnecting the low potential side of said source to said cathode, andmeans connecting the high potential side of said source to a potentialnodal point on each of the linear elements comprising said anode system,and means connectiong an intermediate potential point on said source toa potential nodal point on each of the linear elements comprising saidadditional electrode system.

4. An ultra-high frequency oscillation generator comprising a straightcathode, an anode system comprising a pair of straight parallelconductors defining a plane in which said cathode does not lie, saidconductors being arranged parallel to said cathode and being of suchlength as to have an inherent resonant frequency approximating thefrequency to be generated, means for impressing a high positivepotential on said anode system with respect to said cathode, anadditional electrode system comprising a pair of straight parallelconductors defining a plane intersecting the plane formed by said anodesystem, and means for applying a potential to said additional electrodesystem intermediate the potential of said cathode. and said anode.

5. An oscillation generator as claimed in claim 3 including means forapplying an intense magnetic field to the electron discharge device in adirection parallel to the electric field between the elements thereof.

a 6. An oscillation generator as claimed in claim I 3 including meansfor applying a magnetic field along the vdirection of electron flowbetween cathode and anode.

ROSS GUNN.

